This paper describes an image analysis technique for the counting of nuclei in mitosis in tissue sections. Five experienced pathologists scored mitoses in photographs of preselected areas of tissue sections of the breast. Objects consistently labelled as mitotic cells by all five pathologists were considered "mitoses" in the analysis. In total, there were 45 mitotic nuclei, 68 possible mitotic nuclei and 1,172 nonmitotic nuclei.The image analysis procedure was designed to give priority to a low false negative rate, i.e., misclassification of mitoses. The procedure consists of three steps:1. Segmentation of the image.
Reduction of the number of nonmitoticnuclei by using feature values based on the brightness histogram of the objects. 3. Fully automatic classification of the remaining objects using contour features.The objects remaining after the first two steps were visualized in a composite display for interactive evaluation: 10% of the mitotic nuclei were missed, and 85% of the nonmitotic nuclei were eliminated. The result of the fully automatic procedure described in this paper is rather disappointing and gave a loss of 37% of the mitoses while 5% of the nonmitotic nuclei remained.Key terms: Image analysis, mitotic activity, tissue sections, automated analysisIn the sixties, when digital image processing entered the biomedical area, single cells were among the first topics to be studied. Due to the increased data acquisition and processing capabilities, entire cytological specimens are now ready to be analyzed. At the present time systems are operational for the screening of cervical smears (8,23,27) selection of well-spread metaphases in the field of cytogenetics (6), and automated analysis of blood smears (13,14).In these screening systems, the use of single cell specimens in a monolayer suspension still is essential. Monolayers are obviously not present in a major part of diagnostic practice: tissue section analysis. As a result of this complication, the literature on the analysis of tissue sections is quite limited. The main issues have been the nuclear architecture of the epithelium of urinary bladder (4,25), intercorrelation of nuclear chromatin features in breast cancer (221, and the texture of the chromatin pattern of nuclei in endometrial hyperplasia and carcinoma (7).Apart from the presence of multilayers of cells, several factors complicate the quantitative analysis of tissue sections.